Due to the remarkable development of information communication technology and semiconductor technology, the prevalence and use of portable electronic devices are rapidly increasing. Examples of the portable electronic devices include portable terminals for voice and video calls, MP3 players, and Portable Multimedia Players (PMP).
In particular, recent portable terminals provide a variety of new functions, such as multimedia, wireless Internet, Near Field Communication (NFC), and mobile broadcast reception, as well as traditional communication functions, such as voice call or text message service. In addition, recent portable terminals are under developments in terms of size, design, resolution, and user interface.
Due to this trend, touchscreens capable of performing both data input and data output have been applied to portable terminals. A touchscreen is an input/display device that performs data input and data output on a single screen. To be specific, data output is performed by a Liquid Crystal Display (LCD) panel, and data input is performed by a transparent touch panel disposed on the LCD panel. Such a touchscreen eliminates the use of an existing keypad (for example, an input device using a mechanical metal dome), leading to an increase in a display area and enabling a user to manipulate the touchscreen intuitively. Therefore, portable terminal manufacturers have paid much attention to touchscreens and have conducted extensive research and development in relation to the touchscreens.
Meanwhile, in the case where a touchscreen is employed in a portable terminal, the screen size (less than several inches) of the touchscreen is smaller than that of a general display device such as a computer monitor, and therefore, it is unsuitable for fully displaying various menus of the portable terminal (for example, an address book) or a high-resolution image on a single screen. To supplement this limitation, the touchscreen is provided with a scroll function.
In a conventional touchscreen, a scroll function is performed in such a manner that a user drags his or her finger on a scrollable screen continuously and repetitively. If a large-capacity image displayed on the touchscreen is scrolled using the conventional scrolling method, it may be difficult to find a current position, and a continuous and repetitive touch may degrade the use feeling of the touchscreen.